Mac OS X Server is built on a fully compliant UNIX foundation. This battle-tested core provides the stability, performance, and security that organizations require. And full UNIX conformance ensures compatibility with existing server and application software. Mac OS X Server is the ideal platform for deploying groundbreaking enterprise applications and services.
Open source foundation.
At the heart of Mac OS X Server is the Mach 3.0 microkernel — based on the OSF/mk project from the Open Source Foundation. The Mach kernel provides services for memory management, thread control, hardware abstraction, and interprocess communication. In addition, Mac OS X Server includes the latest technological advances from the open source BSD community. Originally developed at the University of California, Berkeley, the BSD distribution is the foundation of most UNIX implementations today. Mac OS X Server is based largely on the FreeBSD distribution and includes the latest advances from this development community.
UNIX conformance.
Mac OS X Server is an Open Brand UNIX 03 Registered Product, conforming to the SUSv3 and POSIX 1003.1 specifications for the C API, Shell Utilities, and Threads. Since Mac OS X Server can compile and run all your existing UNIX code, you can deploy it in environments that demand full conformance — complete with hooks to maintain compatibility with existing software.
Fine-grained multithreading.
The kernel in Mac OS X Server provides superior thread management and affinity algorithms for efficient handling of multithreaded applications on the latest generation of Intel multicore processors. It also provides precise control of real-time processing requirements, allowing a user-level thread — even an unprivileged one — to precisely specify its requirements for time-sensitive operations. Mac OS X Server implements the complete POSIX threading model (from the POSIX 1003.1c standard), ensuring that each thread can be scheduled independently for maximum efficiency.
Optimized with Grand Central Dispatch. 
More cores, not faster clock speeds, drive performance increases in today’s CPUs. A new technology in Snow Leopard called Grand Central Dispatch takes full advantage of multicore processors by making all of Mac OS X multicore aware and optimizing it for allocating tasks across multiple cores and processors. Grand Central Dispatch also makes it much easier for developers to create programs that squeeze every last drop of power from multicore systems. Learn more about Grand Central Dispatch
Tapping GPU power with OpenCL.
OpenCL (Open Computing Language) makes it possible for developers to efficiently tap the vast gigaflops of computing power currently locked up in the graphics processing unit (GPU). With GPUs approaching processing speeds of a trillion operations a second, they’re capable of considerably more than just drawing pictures. OpenCL takes that power and redirects it for use in high-performance computing applications like genomics, video encoding, signal processing, and simulations of physical and financial models. Learn more about OpenCL
Advanced server features.
While Mac OS X Server is built on the same robust UNIX architecture as Mac OS X, it adds industrial-strength features required for business-critical server deployments. Designed for “headless” operation, Mac OS X Server enables administrators to install and configure services without needing to connect a display to the server. Powerful remote administration tools permit secure service management from anywhere on the network or over the Internet, and support for SSH provides secure access from the UNIX command line. To keep critical services up and running, Mac OS X Server has built-in tools for monitoring systems, preventing accidental shutdown, and recovering services quickly in case of network or power failure.
Watchdog.
For maximum availability, Mac OS X Server includes a watchdog process that continuously monitors activity and recovers services in the event of an application, system, or power failure.
Automatic restart.
Mac OS X Server can be set to restart automatically in case of a power failure or catastrophic system failure.
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